Not too familiar with Dr. Peterson?
This is a great introduction. He gets contraception wrong (thinks it's a good thing), but the rest is mighty fine.
Of course, Natural Family Planning is a good thing, but it is qualitatively different from contraception and a completely different lifestyle. In fact, the difference between contraception and Natural Family Planning is so huge that JP2G called it: "two irreconcilable concepts of the human person and of human sexuality" (Familiaris consortio, 32).